Incidence Based Fetal Urological Counseling Using the Virtual Pediatric Urology Registry: Importance of Insignificant Fetal Pyelectasis (Sonographically Evident Renal Pelvis)

Purpose: Since 1985, counseling for fetal renal pelvic dilatation has been done to determine whether there is need for newborn urological evaluation. This is likely if the anteroposterior width of the renal pelvis exceeds categorical cutoffs, ie 4 mm or greater before gestational age 33 weeks, or 7 mm or greater after 33 weeks. Cases below these categorical cutoffs are deemed not to merit newborn testing. We examined our fetal registry to determine the incidence of urological pathology in cases deemed not to merit newborn testing. Materials and Methods: Since 1980, we have prospectively input fetal ultrasound and postnatal followup data into customized Virtual Pediatric Urology Registry software. The Virtual Pediatric Urology Registry compares index case findings against those archived in the registry and then outputs the incidence of newborn diagnoses. Diagnoses are grouped as having limited or extensive urological care. Results: The Virtual Pediatric Urology Registry has 1,128 cases registered and data on 2,292 fetal ultrasound studies that were done between gestational ages 12 and 43 weeks (average ± SD 29.3 ± 7). There are measurements of anteroposterior pelvic width for 1,712 cases. Pediatric data include ultrasound for 2,596 cases, diuretic renal scan for 449 and voiding cystourethrogram for 574. Surgery was done for renal/bladder obstruction or vesicoureteral reflux in 358 cases (32%). Mean followup was 9.8 months old (range 1 day to 14 years). Of the total of 1,128 fetal cases 148 (13%) showed anteroposterior pelvic width below categorical cutoffs, so that they were deemed not to merit newborn testing. However, the Virtual Pediatric Urology Registry incidence based method identified that extensive urological care extended to 30 of these 148 cases (20%). There were 31 cases identified at less than gestational age 33 weeks, which showed newborn urological pathology in 11 (35%), including hydronephrosis in 4, surgery in 3, vesicoureteral reflux in 2, solitary kidney in 1 and death in 1. There were 117 cases identified at gestational age 33 weeks or greater, which showed newborn urological pathology in 19 (16%), including vesicoureteral reflux in 8, hydronephrosis in 7 and surgery in 4. Conclusions: We found that about 13% of cases of fetal renal pelvic dilatation were insignificant because the measurement was below currently accepted cutoffs that merit postnatal followup. However, 20% of these cases in fact showed extensive urological care needs. The Virtual Pediatric Urology Registry provides an array of likely newborn diagnoses in neonates. Counseling by the incidence based method is more effective than by the current cutoff method.